Mister Roberts is aboard a US cargo ship, working in the Pacific during the Second World War. He'd do anything to leave the quiet of the ship to join in the "action". Trouble is, the captain of the ship, is a bit of a tyrant, and isn't willing to sign Roberts' transfer requests. Also on board is Ensign Pulver, who avoids work as best he can, whilst living off the riches of his buying and selling. Roberts and the crew are in constant battle, even over the smallest of disagreements.